The organic electroluminescence (EL) light emitting device including an organic EL element has been put to practical use as a light emitting device allowing planar light emission. The organic EL light emitting device is used for a display and lighting equipment, and is expected to be further developed.
However, when the organic EL light emitting device is driven for a certain period, a non-light-emitting portion called dark spot is generated and grows, leading to deterioration in light emitting characteristics. A cause of generation of such a dark spot includes influence of water such as water vapor. Intrusion of an extremely small amount of water also has a great influence on characteristics of the organic EL element.
The organic EL light emitting device therefore requires suppression of deterioration in the organic EL element due to water to improve reliability. In a previously provided method to prevent deterioration in the organic EL element due to water, the organic EL element is covered with a sealing component including a barrier film, and a moisture absorbent is disposed within the sealing component (for example, see PTL 1, PTL 2, and PTL 3).
PTL 1 describes an organic EL light emitting device having a configuration in which the organic EL element is covered with a transparent multilayer barrier including a double barrier film, and a moisture absorbent is disposed in each of the inner and outer barrier films. PTL1 describes that the organic EL element is doubly covered with the barrier film including the moisture absorbent and thus improved in moisture-proof property.
PTL 2 describes an organic EL light emitting device, in which the organic EL element is sealed by a resin sealing layer, and a protective layer including a metal foil is provided over the resin sealing layer, and a moisture-absorbing layer is provided at a position so as to surround a light emitting region of a light emitting layer between the resin sealing layer and the protective layer. PTL 2 describes that the moisture-absorbing layer is formed to an outer side beyond an end of the light emitting region, and the resin sealing layer is formed up to the outside of the moisture-absorbing layer, thereby water intruding in the resin sealing layer is efficiently absorbed by the moisture-absorbing layer.
PTL 3 describes an organic EL light emitting device, in which an organic EL element is covered with a gas barrier sheet including a gas barrier film and a moisture-absorbing film, and the moisture-absorbing film is provided at a position so as to cover a top and a side surface of the organic EL element. PTL 3 describes that the side surface of the organic EL element is covered with the moisture absorbent layer, which suppresses influence of water on the organic EL element.